Determinants of soil organic matter chemistry in maritime temperate forest ecosystems

While the influence of climate, vegetation, management and abiotic site factors on total carbon budgets and turn-over is intensively assessed, the influences of these ecosystem properties on the chemical complexity of soil organic matter (SOM) remains poorly understood. This study addresses the chemical composition of NaOH-extracted SOM from maritime temperate forest sites in Flanders (Belgium) by pyrolysis-GC/MS. The studied forests were chosen based on dominant tree species (Pinus sylvestris, Fagus sylvatica, Quercus robur and Populus spp.), soil texture and soil-moisture conditions. Differences in extractable-SOM pyrolysis products were correlated to site variables including dominant tree species, management of the woody biomass, site history, soil properties, total carbon stocks and indicators for microbial activity. Despite of a typical high intercorrelation between these site variables, the influence of the dominant tree species is prominent. The extractable-SOM composition is strongly correlated to litter quality and available nutrients. In nutrient-poor forests with low litter quality, the decomposition of relatively recalcitrant compounds (i.e. short and mid-chain alkanes/alkenes and aromatic compounds) appears hampered, causing a relative accumulation of these compounds in the soil. However, if substrate quality is favorable, no accumulations of recalcitrant compounds were observed, not even under high soil-moisture conditions. Former heathland vegetation still had a profound influence on extractable-SOM chemistry of young pine forests after a minimum of 60 year

Status of Lion (Panthera leo) and Spotted Hyena (Crocuta crocuta) in Nechisar National Park, Ethiopia

Globally large carnivores are in decline due to a combination of habitat degradation and direct human persecution. A survey was conducted in Nechisar national park, Southern Ethiopia to investigate the population status of lion (Panthera leo) and hyena (Crocuta crocuta). Eleven callups were performed; a total of two adult male lions and six spotted hyenas responded. Estimates give a lion density of between 2 and 5 per 100 km2 or a total population estimate of 7 to 23 lions and a hyena density of between 4 to 8 hyenas per 100 km2 or a total population estimate of 17 to 34 hyenas. These estimates include extrapolation to a heavily encroached area where large carnivores are unlikely to occur. The lion population is probably limited to the visually confirmed four individuals. The carrying capacity of Nechisar national park, excluding livestock, is 21 lions and 48 hyenas. The resident agro-pastoral communities who are living with their livestock inside and adjacent to the national park are in conflict with carnivores. This might account for the low density of lion and hyena in the park, and perhaps might result in local extinction within a few years.Keywords: Callups, Hyena, Lion, Nechisar, Density, Ethiopia

Strategy for the identification of micro-organisms producing food and feed products : bacteria producing food enzymes as study case

Recent European regulations require safety assessments of food enzymes (FE) before their commercialization. FE are mainly produced by micro-organisms, whose viable strains nor associated DNA can be present in the final products. Currently, no strategy targeting such impurities exists in enforcement laboratories. Therefore, a generic strategy of first line screening was developed to detect and identify, through PCR amplification and sequencing of the 16S-rRNA gene, the potential presence of FE producing bacteria in FE preparations. First, the specificity was verified using all microbial species reported to produce FE. Second, an in-house database, with 16S reference sequences from bacteria producing FE, was constructed for their fast identification through blast analysis. Third, the sensitivity was assessed on a spiked FE preparation. Finally, the applicability was verified using commercial FE preparations. Using straightforward PCR amplifications, Sanger sequencing and blast analysis, the proposed strategy was demonstrated to be convenient for implementation in enforcement laboratories